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Simple reaction time on light and sound stimulus during different phases of menstrual cycle

Influencing many neurotransmitter systems, estrogen and progesterone change the activation level during different phases of the menstrual cycle. Therefore it may be expected that efficiency will be better during the phases characterized with higher levels of these hormones in comparison with phases when the hormone level is low. The aim of this study was to examine changes of simple reaction times on light and sound stimulus, together with general and high activation level, during different phases of the menstrual cycle. 19 healthy female subjects, aged 18 to 24, with regular menstrual cycle took part in the study. Their ovulatory cycles were confirmed by measurements of basal body temperature. The investigation included measurements of simple reaction times on light and sound and the activation level during four different phases of the menstrual cycle. Thayer's Activation-Deactivation Adjective Check List was used for general and high activation level measures. The results showed shorter RT on both light and sound stimulus during the late follicular and luteal phase, when the hormone levels are high. Longer reaction times in menstrual and early follicular phase were expected because of a decreased level of estrogen and progesterone. The differences in the efficiency may be attributed to different hormones level during the menstrual cycle. The longitudinal design of the study and the subjective nature of the check-list measure may explain insignificant changes of the assessments of both activation levels in this study. Furthermore, different curve profile for sound and light responses may be determined by both stimulus modality and intensity.

menstrual cycle; sex hormones; reaction time

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